package 字符串;

import java.util.Scanner;

public class 奇变的字符串 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String n = scanner.next();
        char[] chars = n.toCharArray();
        String str = "";
        for (int i = 1; i < chars.length; i=i+2) {
            str = str + chars[i];
        }
        StringBuilder a = new StringBuilder(str);
        a.reverse();
        char[] chars1 = a.toString().toCharArray();
        for (int i = 1,j=0; j < chars1.length; i=i+2,j++) {
            chars[i] = chars1[j];
        }
        System.out.println(chars);
    }
}
